The U.S. Border Patrol agent who allegedly shot across the Rio Grande into Mexico, killing a 15-year-old Mexican boy, has been on regular duty for the past two months, officials said this week.

The 31-year-old agent, whose name was withheld by the government, has been with the border patrol for seven years.

Michael Przybyl, assistant chief patrol agent for the U.S. Border Patrol, El Paso Sector, said the agent was placed on administrative duty for a couple days after the June 7 shooting before returning to patrol.

Killed in the shooting was Mexican citizen Sergio Adrían Hernández Güereca. The border patrol said the agent fired after coming under attack by people throwing rocks.

Hernández died on the Mexican side of the river from a bullet wound to the head.

Przybyl said his agency is not investigating the shooting, but the U.S. Justice Department in June said a civil rights investigation would be conducted.